MOSAICKING OF ORTHORECTIFIED AERIAL IMAGES

Aerial photographs are widely used in surveying, geographic informatio n systems (GIS), and other applications. Analysis of a large area requ ires the creation of an image mosaic, which is composed of several aer ial photographs. In an ideal situation, a perfect mosaic can be genera ted using a series of rigid transformations on the source images. In p ractice geometric metric distortions and radiometric differences inter fere with the mosaicking process. In this paper a complete algorithm t o mosaic images taken at different times and conditions with geometric distortions and radiometric differences is presented. The algorithm, which works without any human intervention, integrates global feature matching algorithms into the process of selecting a seam line. The alg orithm may be applied to mosaic any set of images for which an appropr iate matching algorithm exists. The creation of an image mosaic is acc omplished using local transformations along a computed seam line and a rigid transformation elsewhere. An automatic stereo matching algorith m, originally developed for surface height measurement, is used to det ect matching pairs of tie points across frame boundaries. These tie po ints are used to compute the seam line for the mosaic, and to compute geometric and radiometric correcting transformations around this seam line.